For some reason not many RoR developers know that they can extend ActiveRecord associations. This feature can be a great way to cleanup any relational code that is dependent on a parent resource (or to just add a simple functionalities to scopes). Here’s a really simple example how you can use it:

class User < ActiveRecord::Base
module GroupActions
# Here you work on a scope
def reactivate!
# I know we could use update_all - this is not the case ;)
map(&:reactivate!)
end
end
belongs_to :group
def reactivate!
update!(active: true)
end
end
class Group < ActiveRecord::Base
has_many :users, extend: User::GroupActions
end

That way you can perform actions like this one:

# Looks much better than any method like current_group.reactivate_users!
current_group.users.reactivate!

Dynamic pagination (changeable per page on a parent resource)

You can also use a small trick to access parent model and it’s data. It can be useful for example when implementing a dynamic pagination model (based on a parent key value) or any other functionality that somehow depends on a relation owning model. Instead of doing something like this in your controllers: